• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Historical Tidbit

KellenVancouver

Addicted to Fun and Learning
Joined
Nov 16, 2021
Messages
822
Likes
5,768
Martin started a thread about the recent resurgence in cassette tapes, which stimulated a small sidebar about 78 vinyls. I’m not a vinyl person, but I grew up with them (LPs and 45s, not 78s!) and I got to wondering how they developed as a medium. Plus, I’ve always been curious about why 45 records had the big hole compared to LP records with the little hole. So did some online research and came up with the following which I’m sharing in case it piques interest for anyone else. As they say in England, “Mind the step” which is to say I did this kind of quickly so hopefully there is no incorrect information here, but if something needs correction please point it out and help us all with better knowledge.

When records were first popularized they operated at all range of speeds, from 60 RPM all the way up to 130 RPM. Speeds between 78 and 80 RPM were common by 1910. The big record manufacturer prior to WWI, Grammophone, established 78 RPM as its standard speed in 1912, but the official 78 RPM speed (technically, 78.26 RPM) was not standardized until 1925. This was done for manufacturing reasons, in conjunction with the National Association of Broadcasters, to accommodate the typical 3,600 RPM motor using a 46-tooth gear (3600 divided by 46 = 78.26).

Those older 78s were generally made of a shellac resin. That’s why you’ll sometimes hear 78s referred to as “shellac records.” When the country entered WWII, shellac supplies dwindled. That’s when the industry turned to making records with vinyl (which also had the advantage of not being as brittle as shellac).

The big downside of a 78 was that a typical 10-inch record could only play about four minutes of music, which was not enough for a symphony. To solve that problem, in 1931 Radio Corporation of America (RCA) introduced a new type of 12-inch record. Working with another big name at the time, Vitaphone, they matched that 12-inch record with another new innovation, “talkie” motion picture film. A reel of talkie film lasted 11 minutes. Using the standard 3600 RPM phonograph motor, they made a record that would match that same 11 minutes, and that is what gave birth to the rotational speed of the 33.33 RPM record.

Unfortunately for RCA, the Great Depression bombed sales of their 33 RPM records and players (record industry sales fell an incredible 95% from 1930 to 1931). People just stayed with their 78s and were not about to spend money on RCA's new fangled 33 RPM idea. Given the lack of sales, and perhaps showing a monumental lapse of judgment, RCA let their patents associated with the new 33 RPM record expire.

Meanwhile, Columbia Records took RCA’s 33 RPM technology and advanced it with vinyl records. Columbia managed to produce vinyl records with grooves much more closely spaced than on the old 78s, what came to be known as “microgrooves.” That more than doubled the maximum listening time on a 33 RPM record from 11 minutes to 24 minutes. Naturally, those improvements became popular with a public that was in a buying mood after WWII.

Poor RCA was really ticked about all this. Their own technology was being used against them. Because they let their patents expire, Columbia was killing them with 33 RPM vinyl records. To fight back, RCA came out with their own 7-inch diameter record that would spin at an entirely new speed, 45 RPM.

RCA didn’t select 45 RPM just to be different (and no, it has nothing to do with the equation 78-33=45). Instead, 45 RPM was selected to improve fidelity for a 7-inch record. The greatest fidelity in a record is toward the outside edge due to velocity as it spins; with a greater velocity, it can store information on a longer groove surface and thus have lower distortion. A seven-inch diameter record suffers from lower fidelity since it starts with less velocity than a 12-inch record. However, by increasing the speed 35% to 45 RPM, RCA gained a 35% increase in groove velocity and better sound. Of course the trade-off was the record could just play one song per side. That’s where the hole comes in.

RCA made the 7-inch record with a much bigger hole, 1.5 inches in diameter. That compared to the standard center hole diameter for a 33 (based on the sized used by 78s) of 9/32 inch. There were three primary reasons for that. First, RCA’s idea was that by stacking their 45 records on a six-inch tall by 1.5-inch diameter spindle they could achieve much greater overall listening time than the maximum 24 minutes attained by a 33 RPM record. A record player that automatically dropped the next record into place on the six-inch spindle (which was easier to accomplish with a wider diameter) could play up to 60 minutes of continuous music, more than double the time of a Columbia 33 RPM record.

Another reason was RCA wanted to be like today’s Apple, have a proprietary system that would force customers into buying their products. Lastly, there was a technical reason. Dropping a record spinning at 45 RPM onto a 9/32-inch spindle would quickly torque and distort the center hole, making it go out of round, thus introducing wobbliness into the spin of the record. Not good, so the larger diameter hole was the answer to maintaining a perfect spin longer. And that was especially important for a big industry at that time, jukeboxes. Jukeboxes could not afford to have records go out of round quickly, so the 45s with their larger, more stable hole became rather perfect (and ubiquitous) for jukeboxes.
 
OP
KellenVancouver

KellenVancouver

Addicted to Fun and Learning
Joined
Nov 16, 2021
Messages
822
Likes
5,768
BTW, another kind of funny moment when it comes to 45 records. I was at a conference a few years ago and one of the breakout sessions focused on generational differences in the workforce. The presenter conducted an experiment with the audience. He held up a 45 record spindle adapter (the little plastic insert that allows a 45 to be played on an LP spindle) and asked anyone 25 years old or younger in the audience to identify it. There were a range of rather comical answers, but the one that I remember best was the young gal who thought it was an IUD...
 

pozz

Слава Україні
Forum Donor
Editor
Joined
May 21, 2019
Messages
4,036
Likes
6,824
Bump.

Great post.

It reminded me of: flexidisc! Cheap flexible and very small records that used to be sent out in magazines to add an audio side to the stories, or to showcase new music.
 
OP
KellenVancouver

KellenVancouver

Addicted to Fun and Learning
Joined
Nov 16, 2021
Messages
822
Likes
5,768
Bump.

Great post.

It reminded me of: flexidisc! Cheap flexible and very small records that used to be sent out in magazines to add an audio side to the stories, or to showcase new music.
Yes! I completely forgot about those, although I have a decidedly strange one. It came in a book about a country called Tanu Tuva (no longer in existence, subsumed into the Soviet Union prior to WWII). The book included a bright red "floppy" record that was a recording of native Tanu Tuvan singing. Very different because they had a technique of whistling at the same time they sang their song. Probably the strangest music I've ever heard.
 

Katji

Major Contributor
Joined
Sep 26, 2017
Messages
2,990
Likes
2,271
Martin started a thread about the recent resurgence in cassette tapes, which stimulated a small sidebar about 78 vinyls. I’m not a vinyl person, but I grew up with them (LPs and 45s, not 78s!) and I got to wondering how they developed as a medium. Plus, I’ve always been curious about why 45 records had the big hole compared to LP records with the little hole. So did some online research and came up with the following which I’m sharing in case it piques interest for anyone else. As they say in England, “Mind the step” which is to say I did this kind of quickly so hopefully there is no incorrect information here, but if something needs correction please point it out and help us all with better knowledge.
I did not buy many singles - quickly went to buying albums - but I only had one or 2 that had the big hole and afaik/iirc it was because someone had broken out the centre piece. Turntables - at least the typical Japanese ones - generally/usually came with plastic things for the big holes.
Note: some singles had triangular centre pieces, most had round ones with 4 points of attachment.
 
Top Bottom